U1333 – Control Module Communication Fault

The ODBII code U1333 indicates a communication fault between control modules in a vehicle, suggesting that one or more modules are not properly communicating with each other.

The severity of ODBII code U1333 is moderate.

Common Causes For: U1332 U1332: “Control Module Communication Failure”

• Faulty control module
• Poor electrical connections
• Damaged wiring harness
• Corroded connectors
• Software issues or bugs
• Low battery voltage
• Interference from aftermarket devices
• Faulty CAN bus communication
• Grounding issues
• Faulty sensors or actuators

Common misdiagnosis for U1333 U1333: “Control Module Communication Fault”

• Faulty control module
• Wiring issues
• Poor ground connections
• Corroded connectors
• Software glitches
• Battery or charging system problems
• Intermittent faults in communication lines
• Faulty sensors or actuators

Common Troubleshooting Steps

The OBD-II code U1333 indicates a “Control Module Communication Fault.” This code typically means that there is a problem with communication between the vehicle’s control modules. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the control modules. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the wiring harnesses that connect the affected modules.
• Check Power and Ground:
• Ensure that the control modules have proper power and ground connections. Use a multimeter to check for voltage and continuity.
• If there are issues with power or ground, repair the wiring as necessary.
• Test Control Modules:
• If possible, test the affected control modules to ensure they are functioning correctly. This may involve using specialized diagnostic tools or swapping with known good modules.
• Check for any software updates or reprogramming that may be required for the modules.
• Inspect the CAN Bus:
• The communication between control modules often occurs over a Controller Area Network (CAN) bus. Inspect the CAN bus wiring for damage or shorts.
• Use a scan tool to monitor the CAN bus for any irregularities in communication.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the communication between control modules. This includes alarms, stereo systems, or other electronic devices.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the trouble codes using the OBD-II scanner.
• Take the vehicle for a test drive to see if the code reappears. Monitor the vehicle’s performance and any warning lights.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to U1333.
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or dealership for further diagnosis. They may have access to advanced diagnostic tools and resources. By following these steps, you can systematically identify and resolve the underlying issue causing the U1333 code.